There's also nothing wrong with viewing images at 100% as that's the only way to tell how sharp your images are.

Nope; another, much more reliable method is to simply make a decently-sized print from it.

Nonsense. If you have a decent quality display you can much more easily determine the level of sharpness than in a print. The printing stage degrades image quality to a certain degree.. As it relates to sharpness, viewing a digital picture on your computer is like looking at a negative or slide with a loupe.

The typical monitor only has around 100 pixels/inch resolution. Some are higher. Printers often can exceed those resolutions. Inks and paper are critical elements in realizing that. Where monitors excel over printers is in contrast-ratio - which is much higher in the case of the typical monitor.

The ability of good monitors of today to show you the true sharpness of your images is not dependent on it being able to display the pixel density needed to produce high quality photographs. Two separate things.

Color and contrast are what make an image "pop". Sharpness tends to be associated with good color and contrast. Not all images need to be ultra-sharp, but all images benefit from good contrast. Ultra-sharp for portraits requires some softening in post-processing.

So, after spending a lot of time on photography sites, blogs and forums, one thing that seems to always be mentioned is lens sharpness.

There seems to besort of an obsession about sharpness that always generates flaming debates about sharpness, bad copies, sample variation and such...

This got me wondering... Do we really need more and more sharpness? For portraits, events, models... is super sharpness even a good thing? How much is enough? And why do people get so turned on by this?

To many, craftsmanship matters. A good, sharp lens is a necessary (but by itself, not sufficient) tool for crafting nice sharp images, whether for print or screen. Not all subject requires all of the resolution available in modern lenses, nor is max resolution required for all media. Thought it is nice to have if you need it for a particular situation.

It's also one of the more or less quantifiable aspects of lens performance, and a proxy for overall lens quality. So in the endless discussions of price versus quality, it's an obvious target for obsessive debate.

Yes, there's still room for sharper lenses since there's always a desire for better, smaller, cheaper. Whether the state of the art is good enough for you (or me) is entirely an different question.

There's also nothing wrong with viewing images at 100% as that's the only way to tell how sharp your images are.

Nope; another, much more reliable method is to simply make a decently-sized print from it.

Nonsense. If you have a decent quality display you can much more easily determine the level of sharpness than in a print. The printing stage degrades image quality to a certain degree.. As it relates to sharpness, viewing a digital picture on your computer is like looking at a negative or slide with a loupe.

The typical monitor only has around 100 pixels/inch resolution. Some are higher. Printers often can exceed those resolutions. Inks and paper are critical elements in realizing that. Where monitors excel over printers is in contrast-ratio - which is much higher in the case of the typical monitor.

The ability of good monitors of today to show you the true sharpness of your images is not dependent on it being able to display the pixel density needed to produce high quality photographs. Two separate things.

Color and contrast are what make an image "pop". Sharpness tends to be associated with good color and contrast. Not all images need to be ultra-sharp, but all images benefit from good contrast. Ultra-sharp for portraits requires some softening in post-processing.

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NancyP

There is no such a requirement to soften portraits. Some of the most interesting portraits are those that are razor sharp.

There's also nothing wrong with viewing images at 100% as that's the only way to tell how sharp your images are.

Nope; another, much more reliable method is to simply make a decently-sized print from it.

Nonsense. If you have a decent quality display you can much more easily determine the level of sharpness than in a print. The printing stage degrades image quality to a certain degree.. As it relates to sharpness, viewing a digital picture on your computer is like looking at a negative or slide with a loupe.

The typical monitor only has around 100 pixels/inch resolution. Some are higher. Printers often can exceed those resolutions. Inks and paper are critical elements in realizing that. Where monitors excel over printers is in contrast-ratio - which is much higher in the case of the typical monitor.

The ability of good monitors of today to show you the true sharpness of your images is not dependent on it being able to display the pixel density needed to produce high quality photographs. Two separate things.

Your words make very little sense.

Which part did you not understand?

The brief declarations that you have not made an effort to explain. You could start by defining what you actually mean by "sharpness". The ability of a medium to depict spatial frequency information depends upon the maximum contrast-ratio as well as the spatial frequency response characteristics. Perhaps that is what you had in mind - but nobody will ever know if you don't explain what you are talking about, so readers can determine your actual understanding of the subject. Please elaborate ...

it's vague because it is not quantified in a universally accepted way, DxOmark did the best job they could by introducing standardized test methods and the principle, "perceptual mpx"

but these type of quantification are a far cry from what one would consider workable in the world of science.

one should consider an entity defined if it can be presented in vector or scalar form with SI units. pMp is a good unit for sharpness only if the tests used to generate these quantities are perfect and its results free from all outside influence.

the concept of sharpness cannot free itself from these constraints because it is too complex a principle, and the only way to quantify it is to do what Dxomark did, to standardized and simplify it to a form of resolution.

Colour and contrast, the way the light plays naturally within an image is so important.

And colour, so important, take the RX1 for example, do a search on Flickr for RX1. A whole load of thumbs come up and the first thing you notice is the vivid, vibrant colours.

Sharpness is a nice attribute, but it's really very secondary at pixel level. The VAST majority of images are viewed at HD or much less (cellphone level or tablet) and as such the colour and dynamics of the image are FAR more important.

Optometrist do not correct you vision fully. It makes people feel uncomfortable.

I doubt that very much.

I don't. Both my present and my former optician told me the same thing. Both are/were reputable professionals.

I wonder in what particular respects they modify the optical corrections, and if there exists some common standard numerical amount(s) by which they modify such correction parameters.

I also wondered, but if I asked, I have forgotten the answer. I supposed they know what they are doing. But are we not sidestepping the actual discussion here?

I agree with others, that the sharpness of a lens is a good thing and I think price considerations will keep sharpness freaks in check.

Advances in technology is not driven by a "good enough" attitude. Advances are only possible because lensmakers are obsessed with sharpness, sensor designers are obsessed with pixel count and high ISO noise and customers are obsessed with value for money.

If noone obsessed, we would still be using 1 MP cameras costing 2000 USD.

My wife insists, that all my lenses can look into the future and show how she will look in ten years time, but that is another matter entirely

Optometrist do not correct you vision fully. It makes people feel uncomfortable.

I doubt that very much.

I don't. Both my present and my former optician told me the same thing. Both are/were reputable professionals.

I wonder in what particular respects they modify the optical corrections, and if there exists some common standard numerical amount(s) by which they modify such correction parameters.

I also wondered, but if I asked, I have forgotten the answer. I supposed they know what they are doing. But are we not sidestepping the actual discussion here?

I find that particular information more interesting than the "discussion". First, (the "discussion") is premised upon the usage of a term without clear objective definition that describes a subjective perceptual impression. Like the term "brightness" and the phrase "image quality", "sharpness" is a term that is bound to mean and to constitute different things to different observers.

These kind of (non) discussions are all too common on these forums - and accomplish nothing.

If we are talking about the lens have a minimum of optical aberrations and a correspondingly high spatial frequency response (MTF), then I am all for that. There exists a plethora of other effects (in addition to lens aberrations) that diminish that (de-focusing, diffraction, optical filtering on image-sensors, image-sensor noise sources, de-mosaicing, in-camera and/or post-processing manipulations including noise-reduction, display/printer reslution and contrast-ratio limitations, viewing size, viewing distance, ambient lighting and human visual acuity).

Wishing for a lens that is "soft" is like wishing for an image-sensor with some limited number of photosites. It makes little sense to me to desire to impose limitations over and above all of the limitations that already exist - especially when RAW format recording and digital signal processing offers such a wide "spectrum" of ways by which the final image can be "softened" to taste.

(To me), longing for marginal lenses is akin to dreaming of audio amplifiers with vacuum-tubes so that the linearity, bandwidth, and signal/noise ratio will be compromised, based on some desire to always see the world through a particular type of rose-colored glasses smeared with vaseline. It might sound great for certain limited bandwidth program material, and fail miserably where it comes to reproducing orchestral music replete with critical high frequency information.

I agree with others, that the sharpness of a lens is a good thing and I think price considerations will keep sharpness freaks in check.

Advances in technology is not driven by a "good enough" attitude. Advances are only possible because lensmakers are obsessed with sharpness, sensor designers are obsessed with pixel count and high ISO noise and customers are obsessed with value for money.

If noone obsessed, we would still be using 1 MP cameras costing 2000 USD.

My wife insists, that all my lenses can look into the future and show how she will look in ten years time, but that is another matter entirely

If we had keen vision and feeling of all ordinary human life, it would be like hearing the grass grow and the squirrel’s heart beat, and we should die of that roar which lies on the other side of silence.- George Eliot

The higher the resoluton, the more reach, the smaller and cheaper the camera for the same reach.

D7100 with 70-200 F4 today can produce the resolution of D3X with 300 F4 a few years ago at a fraction of the price (assumming lighting is non-issue). sensor resolution improves year on year for free, but lens resolution improvement is hard and expensive, that is why people get "turned on" if there is a sharp lens, especially if it is cheap, like sigma 35 F1.4 or Nikon 50 F1.8G or Canon 70-200 F2.8 II.

1920x1200 monitors are no longer "pretty common." They are actually rare now. It is also not a 2.4MP monitor, which is no surprise considering there is no such a thing as a 2.4MP monitor.

2048x1152 monitors are close enough you get 2.4 Mpx with just two significant digits and there's plenty of models sporting that resolution being catered to gamers and graphical artists on a budget, but honestly, do you really think it was a point that warranted all this discussion? good freaking Lord.

I want every aspect of the lenses I purchase to be as defect free as possible. As another poster mentioned, pricing controls a person's attitude towards such attributes. If all lenses were free, we wouldn't be having this debate.

The financially-challenged should just "own" their plight and quit clogging these forums with false arguments. For example, as a landscape shooter, medium format digital is what I really should be shooting for capturing detail but the pricing is beyond what I can spend (a Lotto win notwithstanding). I'm not going to sit here, put on airs and justify my chosen format on the basis of technical excellence when cost is the primary deterrent to moving on and upward.

1920x1200 monitors are no longer "pretty common." They are actually rare now. It is also not a 2.4MP monitor, which is no surprise considering there is no such a thing as a 2.4MP monitor.

2048x1152 monitors are close enough you get 2.4 Mpx with just two significant digits and there's plenty of models sporting that resolution being catered to gamers and graphical artists on a budget, but honestly, do you really think it was a point that warranted all this discussion? good freaking Lord.

2048x1152 is a very uncommon resolution, and still not a 2.4MP monitor. As I said, there is no such a thing as a 2.4MP monitor. Photography, and the related hardware, is a technical field besides an artistic one. People need to be corrected when using terms that are obviously incorrect.